In the process of angiography, a contrast agent is typically administered to designated vasculature, and is then imaged by means of a medical imaging modality (such as fluoroscopy). The resulting angiographic images are also known as angiograms. Such angiograms may then be used for constructing a road map of the vasculature, and/or for performing measurements.
WO 08/107,905 to Iddan describes apparatus for use with a portion of a subject's body that moves as a result of cyclic activity of a body system. An imaging device acquires a plurality of image frames of the portion. A sensor senses a phase of the cyclic activity. A medical tool performs a function with respect to the portion. A control unit generates a stabilized set of image frames of the medical tool disposed within the portion, actuates the tool to perform the function or move, in response to the sensor sensing that the cyclic activity is at a given phase thereof, and inhibits the tool from performing the action or moving in response to the sensor sensing that the cyclic activity is not at the given phase. A display facilitates use of the tool by displaying the stabilized set of image frames.
An article by Turski, entitled “Digital Subtraction Angiography ‘Road Map’” (American Journal of Roentgenology, 1982) describes a technique called roadmapping.
U.S. Pat. No. 4,878,115 to Elion describes a method in which a dynamic coronary roadmap of the coronary artery system is produced by recording and storing a visual image of the heart creating a mask sequence, recording and storing another dynamic visual image of the heart after injection of a contrast medium thereby creating a contrast sequence, matching the different durations of two sequences and subtracting the contrast sequence from the mask sequence producing a roadmap sequence. The roadmap sequence is then replayed and added to live fluoroscopic images of the beating heart. Replay of the roadmap sequence is triggered by receipt of an ECG R-wave. The result is described as a dynamically moving coronary roadmap image which moves in precise synchronization with the live incoming fluoroscopic image of the beating heart.
U.S. Pat. No. 4,709,385 to Pfeiler describes an x-ray diagnostics installation for subtraction angiography, which has an image memory connected to an output of an x-ray image intensifier video chain which has a number of addresses for storing individual x-ray video signals obtained during a dynamic body cycle of a patient under observation. A differencing unit receives stored signals from the image memory as well as current video signals and subtracts those signals to form a superimposed image. Entry and readout of signals to and from the image memory is under the command of a control unit which is connected to the patient through, for example, an EKG circuit for identifying selected occurrences in the body cycle under observation. Entry and readout of data from the image memory is described as thereby being controlled in synchronization with the selected occurrences in the cycle.
U.S. Pat. Nos. 5,054,045, 5,457,728, 5,586,201 and 5,822,391 to Whiting generally describe a method of displaying details of a coronary artery lesion in a cineangiogram, by digitally adjusting each frame of the cineangiogram so that the lesion is continually displayed at a fixed location on a display screen. The remaining cardiac anatomy is described as appearing to move, in background, past a stationary arterial segment, thus making the displayed arterial segment easier to identify and to examine by medical personnel. Cineangiographic image frames are digitized and processed by an image processor and the image frames are digitally shifted to place the arterial segment in substantially the same viewing location in each frame. Sequential image frames may be presented to the viewer as a stereoscopic pair, to produce pseudostereopsis. The arterial segment is described as appearing to the viewer in foreground, as if it was floating in front of the remaining cardiac anatomy. Image frames may be further processed to aid examination by medical personnel. Frames are described as being averaged to reduce quantum noise and to blur any structure noise. Frame averaging is described as being used to make numerical measurements of arterial cross-section.
U.S. Pat. No. 5,293,574 to Roehm describes an x-ray fluorographic system which produces a cineangiogram and enables a feature in the image to be identified with a cursor and automatically tracked in subsequent images. The identified feature, such as a suspected lesion in a coronary artery, is located in each x-ray frame of the cineangiogram and the data is described as being displayed such that the feature remains motionless in the center of each successive image.
U.S. Pat. No. 5,809,105 to Roehm describes an x-ray fluorographic system which produces frame images at a low dose rate for both on-line and off-line use. Background noise is filtered by first producing a mask which defines the boundaries of the structural features of interest. The mask is used to select the background pixels for filtering, while enabling the structural pixels to pass unfiltered to the display.
U.S. Pat. No. 6,088,488 to Hardy describes a reference image R that is selected and a region of interest (ROI) that is interactively selected encompassing a desired structure from a sequence of images of a moving structure. This ROI is cross-correlated with other real-time images by multiplication in the Fourier frequency domain, to determine if the desired structure is present in the image. If the structure is present, this image may be averaged with other images in which the structure is present to produce higher resolution adaptively averaged images. The technique is described as being particularly useful in imaging coronary vessels. An alternative embodiment is described according to which the offset of the desired structure is calculated in a series of images. The images are then described as being sorted by this offset, and played back in that order to provide a “movie-like” display of the desired structure moving with the periodic motion.
U.S. Pat. No. 6,195,445 to Dubuisson-Jolly describes a technique of displaying a segment of a coronary artery in a stabilized cineangiogram. A computer system receives a sequence of images of a conventional cineangiogram. A user displays a first image on a monitor and selects a point on an arterial segment. The computer system invokes an image tracking procedure that employs active optimal polyline contours to locate the arterial segment and a fixed point in each of the image frames of the conventional cineangiogram. The computer system produces a stabilized cineangiogram by translating the images to place the arterial segment in substantially the same viewing location in each one of the image frames.
U.S. Pat. No. 6,788,827 to Makram-Ebeid describes an image processing method for processing the images of an image sequence comprising steps of determining image data related to first points of an Object of Interest observed in a first image, said Object of Interest having possible movements, and image data related to correlated points found in a second image of the sequence, and based on said image data, of estimating parameters of sets of transformation functions, which transformation functions transform said first points into said correlated points and, from said parameters, of determining one Warping Law that automatically transforms said given Object of Interest of the first image into the same object in the second image of the sequence for following and locating said Object of Interest in said second image of the sequence. The method is described as being applicable to medical imaging, and X-ray examination apparatus.
U.S. Pat. No. 7,289,652 to Florent describes a medical viewing system for displaying a sequence of images of a medical intervention that comprises moving and/or positioning a tool in a body organ, which tool is carried by a support to which at least one marker is attached at a predetermined location with respect to the tool, comprising means for acquiring the sequence of images, and for processing said images during the medical intervention, wherein: extracting means for automatically extracting at least one marker that is attached to the tool support and that neither belongs to the tool nor to the body organ, and yielding the marker location information; computing means for automatically deriving the tool location information from the marker location information, and enhancing means for improving the visibility of the tool and/or the body organ in order to check whether the medical intervention stages are successfully carried out.
An article by Frangi, entitled “Multiscale vessel enhancement filtering” (Medical Image Computing and Computer Assisted Intervention—MICCAI 1998—Lecture Notes in Computer Science, vol. 1496, Springer Verlag, Berlin, Germany, pp. 130-137) describes the examination of a multiscale second order local structure of an image (Hessian), with the purpose of developing a vessel enhancement filter. A vesselness measure is obtained on the basis of all eigenvalues of the Hessian. This measure is tested on two dimensional DSA and three dimensional aortoiliac and cerebral MRA data. Its clinical utility is shown by the simultaneous noise and background suppression and vessel enhancement in maximum intensity projections and volumetric displays.
An article by Dijkstra, entitled “A Note on Two Problems in Connexion with Graphs” (Numerische Mathematik 1, 269-271, 1959), describes the consideration of n points (nodes), some or all pairs of which are connected by a branch, wherein the length of each branch is given. The discussion is restricted to the case where at least one path exists between any two nodes. A first problem considered is the construction of a tree of minimum total length between the n nodes. A second problem considered is finding the path of minimum total length between two given nodes.
An article by Timinger, entitled “Motion compensated coronary interventional navigation by means of diaphragm tracking and elastic motion models” (Phys Med Biol. 2005 Feb. 7; 50(3):491-503) presents a method for compensating the location of an interventional device measured by a magnetic tracking system for organ motion and thus registering it dynamically to a 3D virtual roadmap. The motion compensation is accomplished by using an elastic motion model which is driven by the ECG signal and a respiratory sensor signal derived from ultrasonic diaphragm tracking.
An article by Timinger, entitled “Motion compensation for interventional navigation on 3D static roadmaps based on an affine model and gating” (Phys Med Biol. 2004 Mar. 7; 49(5):719-32), describes a method for enabling cardiac interventional navigation on motion-compensated 3D static roadmaps.
An article by Zarkh, entitled “Guide wire navigation and therapeutic device localization for catheterization procedure” (International Congress Series 1281 (2005) 311-316), describes research into the development of a system for precise real-time localization of a guide wire tip and therapeutic device, in order to provide assistance in guide wire navigation and accurate device deployment within the coronary arteries with minimal contrast material injection. The goal is described as being achieved by real time monitoring of the guide wire tip and therapeutic device in a sequence of fluoroscopic images, and automatic registration to the 3D model of the artery.
WO 08/007,350 to Sazbon describes a tool for real-time registration between a tubular organ and a device, and a method that utilizes the proposed tool for presenting the device within a reference model of the tubular organ. The proposed tool or markers attached thereto, and the device are shown by one imaging modality and the tubular organ is shown by a different imaging modality, but no imaging modality shows both. Due to the usage of the proposed tool, the registration between the device and the tubular organ is significantly simplified and is described as thus, increasing both speed and accuracy.
At the Transvascular Cardiovascular Therapeutics (TCT) conference held in Washington D.C., USA in October 2008, Paieon Inc. demonstrated the CardiOp-THY system for real-time navigation and positioning of a trans-catheter heart valve.
At the TCT conference held in San Francisco, USA in September 2009, Paieon Inc. demonstrated the IC-PRO Comprehensive Imaging Workstation for providing assistance in cardiac catheterization procedures. The Workstation was described as providing the following functionalities: 3D reconstruction and analysis and left ventricle analysis; Virtual planning of single-stent, multiple-stent, or bifurcation procedures; Device visualization during positioning of single or multiple stenting and post-deployment inflation; Device enhancement, post-deployment analysis and fusion of stent- and vessel images; and PACS/CVIS connectivity.
Direct Flow Medical Inc. (Santa Rosa, Calif., USA) manufactures the Direct Flow valve.
The following references may be of interest:
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